Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? Trying to fix leaking pond with liner-very long

I have a pond that was originally a sediment trap the developer put in as they were cutting in the roads. Basically I got stuck with it. It seemed to be holding water but in looking back perhaps it was just a large amount of rain we had during this short period of time.
My first attempt at fixing it was to just clean it out and also use a bunch of soil from this thing to build up part of the area surrounding my house so I wouldn't have to a railing around my wrap around porch. This made the pond the size it currently is which is approximately 70' X 10' X 30'. It starts out 10' wide goes back 70' in sort of a tear drop shape and is about 30' at the rear. I had hired a person to excavate the pond and as he was doing this I found the soil structure to be composed to a large degree of a clay type material. The soil within this pond varied to a large degree. One area is hard pan over a very light and incredibly fine sort of sand that is yelowish in color. The majority of the rest of the pond is a 1' layer of soil on top of a 2' layer of fine yellowish sand which sits on this gray heavy clay like material. When it was originally done it turned out to be about 4' deep with very steep sides to try too keep the heron out. This leaked immediately. I simply ran water into it about 2X/wk and it was livable. I then got the brilliant idea to line it with some nylon reinforced material that was given to me. When I installed it I used a backhoe to reshape one side of the pond adjacent to a neighboring lot. I dug it deeper and put the soil in that spot and installed the liner in a very poor manner thinking I had a minor leak that a lousy lining job would fix. Well I don't know what happened but I made the pond leak to the tune of about 1' per day.
Now I am about to start lining it with used billboards that I've been acquiring over the last year or so. I have enough to do 3 layers thick. I just got of my second day using a mini excavator that I used to muck out the pond plus make it deeper as well as get rid of anything sharp. There were no rocks but I got rid of a few tree stumps etc.
My main issue and question now is the ground water that is entering the pond. I have a 350 gallon per minute mud pump which keeps up with no problem. Left alone the pond will get nearly 1/2 full with ground water in about 3 days with no rain. Over night it gets about 1' of water in it. The idea I have and what I did before returning the excavator was build a separation about 18" tall across the pond at the lid point. My plan is to cover the perimeter with a single layer of the billboard material in case it rains. I have dug the pond to about 6+ feet and the sloping sides will wash down easily if it rains which, of course will subtract from the depth and make for a lot of extra work. After doing the "rain control" I plan on lining one half as I run the pump to control the ground water. Once I get one end done I'll fill it with water to keep the ground water from pushing up the material and I'll move on to the other side ending up in the center where this littel dam is built.
Does this sound reasonable or are there better ideas?
I don't want to spend $5k on this pond so if this material last 5-8 years I can live with that and will likely be out of this house by then.
The second question I have is navigating the drained pond. The "soil" is incredibly soft when wet and just draining doesn't allow it to get dry. It is not possible to walk on this wet soil without sinking in to the point of being stuck with every step. Is there something I can use a walk board? I was thinking of plywood but trying to pick up a sheet of plywood that is stuck to this stuf will be impossible???
What is odd to me is that this soil, which is mainly the gray clayish type soil at the bottom, is like quick sand and hold water like nothing I have seen but once it drains off it gets very firm-almost hard.
Very sorry for this super long post. Anyone that stuck it out and wishes to make some suggestions is very appreciated.
Thanks
Howard
Hampstead
NC

For walking, use some cheap snowshoes. Works great!

For liner, you can easily find rubber pond liner for well under 5K for a pond that size. You would be best-served just using the rubber pond liner and call it a day. It may have to be welded to make 70', but if you shrunk the pond a little, you may pull it off.

I paid too much for a 20x20 heavy rubber liner, about $800 including underlayment before I got my "real" pond. You can find lighter, cheaper material if 5 years is your goal, but not entirely fair for the next guy.

First search results:
http://www.pondboy.com/items/pond-liner/list.htm
Not recommending anyone, but local shops will carry the stuff. Order a whole roll if possible to use it all. Then use the tools shown to produce a weld for sealing.

I've never used the liner/billboard material but I think that if it's not glued/welded together, then the water will leak out thru the overlapping layers.

I think the water under the liner will cause problems until the water pressure on top of the liner can push it down. I believe they make one way vents for liners to let trapped gasses out. Maybe you could incorporate some of those?

If you had good clay at the bottom, what about digging it deeper, and using that clay to plate and pack over the whole pond basin 18" thick?

Thank you for the suggestions. I don't have the $ for a "real" liner. I know it would be best to go with one but it isn't my plan.
I am not convinced the material I found is indeed clay and even if it were it is in layers and it wouldn't be possible to excavate the required amount to put 18" as a base.
I will look into the valves. This is a good tip.
I plan on using a heavy duty contact cement AND a heavy duty vinyl glue which actually chemical welds the materia Once I use the contact cement I will overlap the seem and "weld" it again. If the liner fails I don't think it will be at the seems.
Of course it poured rain last night. I just returned the excavator and am not looking forward to seeing how much erosion occurred on the sides I built up
No snow shoes in my area I will have to improvise.
Thank
Howard

With the internet, the whole world is your area.

http://tubbssnowshoes.com/

There are others, just the first one I grabbed.